This invention relates to a device for measuring an amount of light reflected by a retina and a gaze detecting apparatus using the same and, more particularly to a gaze detecting apparatus for detecting a gaze of a person in an indirect manner making use of a face image picked up by an image pick-up unit such as a television camera and a retina reflection characteristic to an incident light. The word "gaze" as used herein means the position or direction in which the eye is looking.
Conventionally, a cursor has been moved on a screen of a personal computer, a CAD, and like apparatus with the use of up- and down-keys provided in a keyboard, a mouse, etc. In order to provide a better user interface by reading an intention of the user from his/her gaze, there have also been proposed various apparatuses for detecting a gaze of the user which are attached to a face of the user. Recently, there has been proposed an indirect gaze detecting apparatus which detects the position of a cornea reflected image and a center of a pupil from a face image picked up by a plurality of cameras, and further detects a center of an eye ball from the detected position of the cornea reflected image and center of the pupil. Such an apparatus is disclosed as in Unexamined Japanese Patent Publication No. 2-134130.
The apparatus disclosed in the above publication requires detections of the position of a spot-like cornea reflected image, and the centers of the pupil and eye ball from the face image. Further, a detector for making these detections is required to have exceedingly high level of accuracy. This has caused fabrication of a larger size apparatus and an increase in manufacturing cost.